Bowling alley



rMay 14, 1940- D. B. HINCKLEY BOWLING ALLEY Filed May 10, 193g VIII Patented AMay 14, 1940 UNITED STATES PATENT OFFICE 4 Claims.

the provision of automatic foul line signals responsive to the body capacity of a bowler.

-Another object of the present invention is the enclosure of a pair of automatic capacity foul line signals within a single metal box in such manner that the actuating circuits are not subject to interaction upon each other.

Figure l is a perspective view of a pair of bowling alleys showing the foul line detectors in place.

Figure 2 is a wiring diagram showing the actuating circuits for a pair of foul line detectors.

Figure 3 is enlarged detail view showing the relation of the antenna to the bowling' alley surface.

The present invention relates to electrical means for indicating violation of the foul lines in bowling alleys. -More particularly, the invention relates to the use and special adoption of a so-called Ycapacity relay circuit for use as a foul line indicator in bowling alleys. A single unit of the device consists of a three element vacuum. tube I in conjunction with suitably fixed condensers, C1, Cz, C3 and C4, a variable condenser Cs, a radio frequency choke coil il and a relay l2, the same connected to an antenna I3 which for this particular use is integral with the foul line strip i4. The operation of the capacity relay circuit is such that when the bowler slides his foot over the foul line, or passes it slightly above the foul line, the capacity of the grid circuit of the vacuum tube is thereby affected-as the antenna is connected directly to the tube gridcausing the tube to go into a state of oscilla# tion. Th' state of oscillation in turn causes an increased flow of current through the plate cir cuit, inwhich the relay coil is connected in series. The increased flow of current in the relay coil serves to close the relay contacts I5 thus completing an external circuit and causing a light I9 to be turned on, and a gong to be sounded, or both.

The light may be placed directly on the box IB containing the relay apparatus, or in anyother convenient location.

The box i6 should be located as hear the foul line as is reasonably possible, a convenient location being just under the ball returns I1.

Connections with the relay box for the 1 10 volt and 6 volt circuits are. established through a standard conduit (not shown). The antenna leads VI8 are brought in separately through individual holes in the bottom of the box.

Each circuit is adjusted by means of the varia- I (ci. 27a- 50) Among the objects of the present invention are ble condenser C5 to a point at which the tube lli is near a state o! oscillation. To make this adjustment correctly, a person should stand with one foot just over the foul line, at which time the capacity of C5 should be decreaseduntil the tube goes into oscillation, causing the above described effect.

A Up to the present time, it has been impractical to use more thanv one capacity relay circuit within a single'enclosed metal box, for the reason that the circuits are subject to interaction of one upon the other. This eilect manifests itself in that when one circuit goes into a state of oscillation, because of the laddition of capacity to its antenna,4 the other circuit is also likely to start oscillating, which would obviously be confusing as it would turn on the foul indicating lights or two alleys.

After some study the cause of this interaction has been discovered and also its remedy. The cause is due to the fact that as a result of quantity production ln these units, they are naturally made of identical parts. 'I'his in turn brings about operation on the same frequencies. Each circuit is subject to interference-through inductance or capacity or feed back through the power lines on the frequency to which it is tuned.

Now, the factor in the operation of these units which causes the relay to function is the increased flow-of current through the relay coil when the tube oscillates.l For example, if the tube passes a current oi 1.50 milliamperes when set by C5 to the required degree of sensitivity, it may pass 3.00 milliamperes when in a state of oscillation. Now since the relay contacts l5 will close with a current ilow of say `2.1 milliamperes, this increase in current ilow from 1.5 mils to 3 mils will cause it to operate. Now again this increase in current flow in one circuit induces an added current ilow in the adjacent circuit which is sufficient to bring the current in thatplate circuit from 1.50 mils up to 2.1 mils (since the circuit characteristics are identicaD-which in turn causes the other relay circuit to operate. To remedy this state of affairs, it is necessary that the circuits A and B-which are adjacent in the same box-should be made to operate on different frequencies, in which case they will not be sensitive to changes in current flow, each to the other.

Since the frequency of oscillation is controlled by the combination of ihechoke con Il and the capacity C4 it follows that a change in either of these values will change the frequency of noscillation of the circuit of which' it is a part.

-Ience it is only necessary for satisfactory operation of two of these circuits in close proximity to each other, to make the capacities C4 oi different values, thus causing the aforesaid dif ference in operating frequencies of the two circuits.

However, the difference of frequencies must be such that there is no mathematical relation between them. That is, there must be no common denominator to the different frequencies on which the two operate-For example-if circuit A operates on 4 rnegacycles and circuit B on 6 megacycles there is a common denominator of 2 megacycles. Now these circuits, when in oscillation will set up harmonics on other frequencies than those on which they are oscillating, these harmonics being multiples of some denominator oi each. The circuits also are sensitive to induced currents on these harmonics. it follows that A, operating on 4 megacycles may set up harmonics and 2 or/and 6 megacycies which will be picked up cy B or vice versa thus causing increased current flow in the plate cirn cuits of the other unit and the consequent opera-- fticn of its relay.

This diiiiculty may be overcome by arranging the capacities C4 so that there 'will he no com ion denominator to the frequencies of oscillation ol the 2 circuits. For example circuit A may be .made to operate on 4 megacycles and B on 5 megacycles. While there will be a common multiple of 2i) megacycles for these two frequencies, this seems to be suiciently lar out of range so that it does not affect the satisfactory operation of the two units.

The units are arranged two in a metal box. which is placed below the rise in the ball returns, each unit caring for the foul line on one alley.

The Wiring is carried out in such a way that the warning lights i9 will stay on until turned out. by breaking the contact at a hand controlled switch 2|. These switches must be in the 115 voit feed lines 23 to the units, which may be either DC or AC and not in the 6 volt lines 25 which sup-ply the tube heater current, as if placed in this latter circuit the tube iilamcnts would be allowed to cool each time the control switch 2| was used to turn out a light i5. This would be undesirable as the tube heaters reduire an appreciable time to reach a stable operating temperature.

While the foul line indicator will operate satis factorily with the antenna. strip installed as in A, in any position from the horizontal to the vcrtica` posit-icm. improved operation :is noted when the installation is made as indicated in 3. This angle is about 30 :from the hori aantal.

ciairn:

i.. A device for indicating when a player pas-ses over the foul tine in a howling ailey comprising a radio frequency circuit having' an antenna pesiticnedaiong a line adjacent the foul line, said radio frequency circuit having' a plate circuit are Therefore, A

ranged to have an increased current flow when the capacity of the grid circuit is a'ected by the players loot passing over the foul line, an alarm circuit, electrical means operatively associated with said plate circuit and said alarm circuit and adapted to be actuated to close said alarm circuit in response to said increased current flow, said antenna being in the form of a flat metal strip positioned below the surface of the alley and forming an acute angle therewith.

2. A device :for indicating when a player passes over the foul line in a bowling alley comprising a radio frequency circuit having an antenna positioned along a line adjacent the foul line, said'radio frequency circuit vhaving a plate circuit arranged to have an increased current ow when the capacity of the grid circuit is affected by the players foot passing over the foul line. an alarm circuit, electrical means operatively associated with said plate circuit and said alarm circuit and adapted to be actuated to close said alarm circuit in response to said increased current flow, said antenna being in the form of a flat metal strip positioned below the surface of the alley and forming an acute angle therewith, and a switchfor controlling said alarm circuit.

3. In a' bowling alley having two adjacent playing lanes, electrical means for indicating when a player passes over the foul line in either lane comprising a pair ci radio frequency circuits one having an antenna positioned along a line adjacent the foul line of one lane and the other havingr an antenna positioned along a line adjacent the foul line of the other lane, each of said radio frequency circuits having a plate circuit arranged to have an increased current iiow when the capacity of its grid circuit is affected by the players foot passing over the foul line, a pair of alarm circuits, electrical means operatively associated with said plate circuits and alarm circuitsv and adapted to be actuated tociose an alarm circuit in response to said increased current flow, and means for causing said radio frequency circuits to operate at `diilcrcnt frequencies of oscillation.

4. In a bowling alley having two adjacent playing lanes, electrical means for indicating when a player passes over the foul line in either lane comprising a pair of radio frequency circuits one having an antenna positioned along a line adjacent the foul line of one lane and the other having an antenna positioned along a line adjacc the foul line of the other lane, each ol said r frequency circuits having a plate circuit arran i d to have an increased current;- 'flow when tl. '2 pacity of its grid circuit is oilcctcd by the pi foot passing over the foul line, a pair ci al. circuits, electricai means operatively asniciatcd in response to said l .creased curro `t dow, a a a xed capacity in of said rudio ircq circuits for cauein. einen tu oper at different frequencies; occhi-ation. 

